From a structural standpoint, you may want to consider making the case for your own Space under the top-level community. This is one way to create a "community within a community."

Along with that you would also want to have a dedicated community manager, a clear statement of purpose for your community, a governance model of some kind, and your metrics and reporting in place to at least track community health if not also perceived business value.

Beyond that you would want to make sure you meet at least monthly with the main community's ECM (enterprise community manager).